Citrus Growers Crying for More Weapons to Battle Greening

By KEVIN BOUFFARDTHE LEDGER

Sunday

Aug 25, 2013 at 9:30 PM

After a costly eight-year battle against citrus greening, including a punishing 2012-13 season during which the disease likely caused about 13 percent of the orange crop to drop to the ground before it could be harvested.

LAKE ALFRED | After a costly eight-year battle against citrus greening, including a punishing 2012-13 season during which the disease likely caused about 13 percent of the orange crop to drop to the ground before it could be harvested, Florida growers have implored scientists for a better life preserver."If you're in a lifeboat, you don't reach for the life jacket until the boat starts rocking or it starts taking on water," said Harold Browning, chief operating officer at the Citrus Research and Development Foundation in Lake Alfred, which has spent more than $66 million on greening research to date. "Certainly there's a sense of desperation people felt when they saw all that fruit drop last season."In their desperation, growers since the beginning of the year have called on him and members of the foundation's board of directors, most of them growers themselves, for better short-term solutions to mitigate greening, Browning said, while continuing research on long-term solutions, such a treatment for the disease or new hybrid trees better able to withstand it."The truth of it is all us growers are trying a lot of different approaches. We're trying so many approaches we don't know what is working and what doesn't," said Marty McKenna, a Lake Wales-based grower and chairman of the Florida Citrus Commission. "The drop problem was a very sobering experience."Greening is a bacterial disease that eventually kills trees, thus threatening the viability of commercial citrus growing in Florida. Before dying, the trees produce misshapen fruit with a bitter flavor unfit for human consumption.

'ENHANCED NUTRITION'Until 2012-13, most Florida growers believed they had a viable short-term greening solution with "enhanced nutrition," McKenna said. That's the label for an intensive fertilizer program that includes adding minor nutrients such as boron, manganese and zinc, which the disease appears to rob from citrus trees.Winter Garden-based grower Maury Boyd first developed an enhanced nutrition program in 2006 and showed it would successfully maintain tree health and normal fruit in greening-infected trees. Before greening, trees picked up those nutrients from the soil, so they were not part of standard fertilizer programs.But Boyd's program came under fire because it meant they would no longer remove infected trees, leaving them as a source of greening bacteria that would result in the disease's continued spread across Florida. Many scientists argued the only way to contain greening was to remove infected trees.Within several years, most Florida growers abandoned tree removal and adopted some kind of enhanced nutrition program. Boyd freely shared his data on what supplements to apply, when and how much.That decision seemed justified for the three seasons until 2012-13, McKenna said. Despite the continued spread of greening during that time, resulting in declining grove acreage and tree numbers, Florida's orange harvest increased each year from 133.7 million boxes in 2009-10 to 146.6 million boxes in 2011-12, according to U.S. Department of Agriculture statistics.

PRODUCTION DROPThe orange crop was expected to increase to 154 million boxes in 2012-13, according to the USDA's initial estimate last October. But nobody saw the looming pre-harvest drop problem, which reduced last season's crop down to 133.4 million boxes in the USDA's final estimate in July."Last season was the first season greening from one year to the next impacted our production (since the widespread adoption of enhanced nutrition)," said McKenna, adding most of the drop came on infected trees.The drop problem raised new questions about enhanced nutrition, including which supplements enhance tree and fruit health and which are ineffective, Browning and McKenna agreed. That's when they began pressing the Citrus Foundation for answers."I thought that debate was over," Boyd said.Scientists have not answered many questions about enhanced nutrition programs, said Boyd, adding he supports further research.But Boyd also maintained enhanced nutrition remains the only viable short-term solution in the fight against greening. Certainly returning to tree removal offers no alternative since more than half Florida's more than 69 million commercial citrus trees are infected. "There's no alternative until we get better trees," Boyd said. "We have an endemic disease. We can make trees survive, but like very sick patients in hospital, you can't expect them to jump out of bed and run down the hallway."The Citrus Foundation has spent $4.8 million on 21 projects related to nutrition since its beginning in 2009, Browning wrote in a July "white paper" addressing the topic.Some of those projects will not conclude until 2015, said Browning, who acknowledged the research so far has not answered the key questions on enhanced nutrition.Browning is preparing a follow-up paper that will address the most current findings on nutrition from those researchers, he said. It should be available by October.The foundation is calling for additional research projects on nutrition, Browning said, and how much additional money will be spent on the subject depends upon how many proposals come in by the Sept. 23 submission deadline. After further screening, the foundation's board will approve funding for new project in February.Meanwhile, Boyd, McKenna and growers across the state are watching their groves for signs of a return to last season's pre-harvest drop problem. The early signs are not promising.Early research showed that, while enhanced nutrition can keep citrus trees productive, they lose vigor to the disease. That means they don't tolerate as well as uninfected trees any kind of additional stress, such as weather or damage from other diseases and pests. A consensus shared by Boyd, McKenna and Browning held that a dry spring and summer 2012 caused enough stress on greening-infected trees that they had difficulty holding onto the 2012-13 crop. They and others hoped above-average rainfall this year will alleviate the problem for the 2013-14 crop.But wet weather also aids the spread of citrus canker, another bacterial disease. Canker also weakens trees and leads to pre-harvest drop."It's going on as we speak," McKenna said earlier this week about canker-related pre-harvest drop."Because of the rainfall, we're going to have more of a canker problem," Boyd agreed.Still, canker-related drop likely won't mirror last season's problem, McKenna said."The drought problem was widespread across Florida," he said. "The canker problem is not currently as widespread as the drought."Polk leads the state's citrus-producing counties with 82,572 grove acres and 9.9 million trees in 2012, according to USDA data. It historically leads the state in citrus production, as it did in the 2011-12 season with 31.2 million boxes. It ranked No. 1 in orange, tangerine and tangelo production and third in grapefruit.

[ Kevin Bouffard can be reached at kevin.bouffard@theledger.com or at 863-401-6980. Read more on Florida citrus on his Facebook page, Florida Citrus Witness, http://bit.ly/baxWuU. ]

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